This invention relates to electrical connectors which require a sequence of operations to effect a disconnection.
Push-to-lock electrical connectors are commonly used in automotive wiring harnesses and the like. With the advent of higher voltage and higher current vehicle electrical systems in which positive and negative power terminals are contained in the same housing in close proximity to one another or to terminals from other circuits, it is becoming increasingly common to use connectors with multi-step terminal mating and unmating sequences to prevent arcing. Using first-to-mate/last-to-unmate xe2x80x9cprimaryxe2x80x9d terminals and last-to-mate/first-to-unmate xe2x80x9cpilotxe2x80x9d terminals, for example with the primary terminals on a power circuit and the pilot terminals on a control circuit, the risks of electrical arcing and shock are prevented. The staggered mate/unmate sequence is typically accomplished by making the primary terminals longer and/or by offsetting them relative to the pilot terminals. When male and female connectors with such terminals are coupled and uncoupled, the electrical circuit is made and broken only after the power terminals are fully mated and unmated, preferably while the terminals are still safely within the confines of the coupled connector housings.
Vehicle connector housings also frequently include multi-step locking and unlocking features to ensure positive mechanical and electrical connection, and to prevent unintended separation. The classes of structures commonly known as xe2x80x9cCPAxe2x80x9d (connector position assurance) and xe2x80x9cTPAxe2x80x9d (terminal position assurance) devices are good examples.
It has been known to combine multi-step terminal and multi-step connector functions, for example as in U.S. Pat. No. 6,325,648, in which a lever assist structure on the outside of the connector housings is arranged to complement the staggered make and break sequence of primary and pilot terminals.
A potential disadvantage of multi-step connector locking structures is the feel of the locking motion, which is generally not smooth and uninterrupted. This can result in partial locking of the mechanism due to failure of the person mating the connectors to feel the difference between full and partial connection.
The present invention is a connector housing locking method and mechanism especially, although not exclusively, useful for multi-step terminal connections. Locking the connector housings is a single, smooth, uninterrupted step; once mated, the locking connection is protected against unintended release. Unlocking the connector housings requires a series of independent release steps alternating between manipulation of the locking connection and relative movement of the connector housings in the separation direction. This multi-step unlocking procedure is especially useful with multi-step terminal disconnect arrangements, as the release steps can be timed to ensure a staggered terminal disconnection with a positive mechanical delay between the unmating of the terminals.
In the preferred form, the connector locking mechanism is a one-step insertion, multi-step extraction lock arm arrangement, in which the locking connection is made in the axial insertion direction of the connector housings. Unlocking the connector housings requires stepwise vertical operation of the lock arm alternating with incremental, stepwise withdrawal of the connector housings. In a further preferred form, the locking mechanism is an axially-mating tip of a flexible, cantilevered lock arm extending from one connector housing, and a receptacle on the outside of the mating connector housing for receiving the locking tip in one smooth locking step. The receptacle defines a step-wise unlocking path for the locking tip as the lock arm is sequentially pressed down and the connector housings are sequentially pulled apart. This locking/unlocking mechanism can be operated by one hand if the connector housing with the receptacle is mounted on a fixed object.